I’m skeptical of the supplement industry by default. Walk into any health store and you’ll find walls of products making claims that range from vague to outright fraudulent. Most of it is noise.
So when I tell you I take supplements, I mean a short, deliberately chosen list — each one earning its place through systematic reviews, randomized controlled trials, or both. Not anecdotes. Not influencer stacks. Not whatever Andrew Huberman mentioned this week.
My framework is simple: strong evidence, practical benefit, no unnecessary overlap. If I can’t find solid research supporting something, it stays off the list regardless of how convincing the marketing copy sounds.
Here’s what made the cut, why it made the cut, and exactly how I take it.
Vitamin D3 + K2
What I take: Vitamaze Vitamin D3 5000 IU + K2 (MK-7), one tablet daily at breakfast with food.
Living in Barcelona, you’d think vitamin D deficiency is the last thing I need to worry about. Plenty of sun, right? But if you spend most of your daylight hours indoors — working, commuting, sitting in cafes — you’re not synthesizing nearly as much as you assume. This applies to people in sunny climates just as much as it does in northern Europe. Serum 25-hydroxyvitamin D levels tell the real story, and I’ve had mine tested.
Vitamin D3 is well-established for bone health and immune function. Beyond that, there are associations in the literature with all-cause mortality reduction, though the research here is still maturing and results vary depending on baseline levels. If you’re already replete, supplementing more won’t necessarily help. If you’re deficient — which is common — getting levels into the optimal range has measurable impact.
K2 (specifically the MK-7 form, which has a longer half-life than MK-4) enters the picture because of calcium. Vitamin D increases calcium absorption, which is the point — but calcium needs to go into your bones, not your arterial walls. K2 activates proteins that shuttle calcium to the right places and inhibit arterial calcification. The pairing is synergistic and now well-documented in systematic reviews. Taking D3 without K2 isn’t necessarily dangerous, but it’s an incomplete picture.
Practical note: D3 and K2 are both fat-soluble, which means they absorb poorly on an empty stomach. Always take them with a meal that contains some fat — breakfast works perfectly for this.
Creatine
What I take: Optimum Nutrition Micronized Creatine Monohydrate, 5g daily at breakfast.
Creatine is probably the most-studied supplement in sports science, and the evidence for its effects on strength and power output is as solid as it gets. But I’d be less interested in it if that were the whole story.
What’s caught my attention lately is the emerging research on cognitive benefits. Several trials have now shown improvements in working memory and reduced cognitive fatigue, particularly under conditions of sleep deprivation or high mental load. The proposed mechanism — creatine replenishing ATP in brain tissue — is biologically coherent. The effect sizes are modest, but the research is credible and replicating across independent groups.
Creatine works through saturation of muscle (and brain) stores, not through acute timing. This means there’s no magic window, no need to take it pre-workout, and no loading phase required unless you want to saturate stores marginally faster. What matters is consistency. Taking it every day at breakfast has made it completely automatic for me.
Monohydrate is the form to buy. It’s the form used in virtually all the research, it’s the cheapest, and it’s stable. There’s no credible evidence that fancier forms (creatine HCL, buffered creatine, etc.) outperform it. Save your money. I use Optimum Nutrition’s version specifically because it uses Creapure — creatine monohydrate manufactured by Alzchem in Germany at 99.9% purity. ON is also Informed Choice certified through LGC, an independent anti-doping laboratory, and manufactured by Glanbia in cGMP-audited facilities. For something I take daily, that level of quality control matters.
Omega-3 (EPA/DHA)
What I take: Fish oil providing 1-2g combined EPA+DHA, at lunch with a fat-containing meal.
Here’s the thing that catches people out with omega-3 supplements: the label says “1000mg fish oil” and they assume they’re getting 1000mg of EPA+DHA. They’re not. A standard 1000mg fish oil capsule typically delivers around 300mg of combined EPA+DHA — the rest is other fatty acids and filler oil. You need to flip the bottle over and read the actual EPA and DHA numbers. That’s the dose that matters.
The cardiovascular evidence for omega-3s is solid at meaningful doses. The REDUCE-IT trial demonstrated significant reduction in cardiovascular events using 4g/day of purified EPA (icosapentaenoic acid) in patients with elevated triglycerides. Triglyceride reduction from EPA/DHA supplementation is one of the more consistent findings in nutritional research — not a maybe, a reliable effect at adequate doses.
The DO-HEALTH trial, a large multi-country RCT, found that omega-3 supplementation slowed biological aging markers measured through various biomarkers. This is newer territory, and I take it with appropriate caution, but it fits a broader picture of anti-inflammatory benefit.
I take omega-3 at lunch rather than breakfast for two reasons. First, absorption improves meaningfully when taken with a fat-containing meal, and lunch is typically my largest meal. Second, fish oil with fat reduces the chance of the less-than-pleasant fishy reflux that some people experience. High-quality fish oil (properly stored, not oxidized) helps here too — rancid fish oil is both less effective and more likely to cause GI issues.
What to look for when buying: Check the actual EPA and DHA numbers on the back of the label. Look for IFOS certification (the gold standard for omega-3 purity testing) and triglyceride (TG) or re-esterified triglyceride (rTG) form, which is 50-70% better absorbed than the cheaper ethyl ester form. Brands that use the superior form always advertise it — if the label doesn’t say, it’s probably ethyl ester.
How to store fish oil at home: Keep the bottle in the fridge, especially if you live somewhere warm. Omega-3 fatty acids are highly susceptible to oxidation from heat and light. Keep capsules in the original opaque container — never transfer them to a clear pill organizer on the windowsill. Finish the bottle within 3-4 months of opening. And do the bite test when you open a new bottle: pierce a capsule and smell the oil. Fresh fish oil has a mild, slightly oceanic scent. If it smells pungent or strongly fishy, it’s rancid — throw it away. Rancid fish oil doesn’t just lose its benefits; oxidised omega-3s may actually increase inflammation, which is the opposite of what you’re paying for.
Magnesium Bisglycinate
What I take: Natural Elements Magnesium Bisglycinate — 300mg elemental magnesium per day (3 capsules), at dinner.
Magnesium deficiency is one of the most common nutritional shortfalls in Western diets, driven largely by soil depletion and the shift toward processed food. Whole grains, nuts, leafy greens, and legumes are the best dietary sources — the foods that tend to be underrepresented in how many people actually eat.
The evidence base here is substantial: 77 randomized controlled trials and 17 meta-analyses, covering sleep quality, blood pressure, muscle function, and metabolic health markers. This isn’t a supplement with tentative research behind it.
The form matters more than it does for some other supplements. Magnesium oxide — the form used in cheap products — has poor bioavailability and is the most likely to cause loose stools (it’s been used as a laxative). Magnesium bisglycinate (also called magnesium glycinate) is bound to the amino acid glycine, which improves absorption and eliminates most GI distress at normal doses.
I take it at dinner deliberately. Magnesium supports muscle relaxation and has mild sleep-onset effects through glycine’s role in neurotransmitter regulation. It doesn’t knock you out, but most people notice better sleep quality with consistent use, and taking it at dinner puts timing on your side.
A note on recovery: If you train with weights, you might wonder whether magnesium helps with post-workout recovery. The honest answer is: modestly. A few small RCTs have shown a 16-26% reduction in delayed-onset muscle soreness (DOMS) at 24-48 hours post-exercise. The mechanism is plausible — magnesium is a cofactor in over 300 enzymatic reactions, including protein synthesis and energy metabolism. But the evidence base is thin (a 2024 systematic review found only four qualifying studies with 73 total participants), and the Cochrane review on magnesium for muscle cramps found it doesn’t actually help with cramps, despite what everyone assumes. The biggest recovery benefit from magnesium is probably indirect — through better sleep quality, which is the primary recovery window. So I wouldn’t take it specifically for recovery, but if you already take it for the reasons above, the modest recovery support is a welcome bonus.
Zinc (Chelated)
What I take: Chelated zinc (Solgar’s amino acid chelate form) at breakfast.
Zinc earns its place for immune function, testosterone maintenance, wound healing, and enzymatic processes throughout the body. The evidence is well-established through systematic reviews and RCTs.
I use Solgar’s chelated form because amino acid chelates have better absorption than standard zinc salts, and Solgar is a brand I trust for manufacturing quality. Standard zinc gluconate or zinc citrate are fine alternatives — the main thing to avoid is zinc oxide, which has poor absorption.
Now for the caveat that I want to make sure you don’t miss. This is genuinely important.
Long-term zinc supplementation depletes copper. Zinc and copper compete for absorption in the gut, and consistent zinc intake will suppress copper absorption over time. Zinc-induced copper deficiency is a real clinical condition. Symptoms include anemia that doesn’t respond to iron supplementation, immune dysfunction, neurological problems, and — in serious or prolonged cases — irreversible neurological damage including problems with gait and coordination.
This isn’t a theoretical risk. There are case reports in the literature of people who supplemented zinc for years without accounting for copper and ended up with significant neurological consequences.
The solution is straightforward:
- Supplement copper alongside zinc (1-2mg copper per 15mg zinc is a commonly cited ratio)
- Or ensure your diet provides adequate copper through food (organ meats, shellfish, nuts, and seeds are high in copper)
- Or monitor via blood work — serum copper and ceruloplasmin can detect deficiency before symptoms appear
I have mine checked periodically. If you’re going to supplement zinc long-term, please take this seriously.
What I Don’t Take
Plenty of supplements didn’t make my list, and that’s intentional.
Vitamin C at megadoses — the evidence for supplementing above what food provides is weak for healthy adults. A varied diet handles this.
Multivitamins — they’re convenient but imprecise. You end up taking multiple nutrients you may not need, often in poorly absorbed forms, while potentially masking deficiencies you should actually be addressing. Better to test and target.
Ashwagandha, lion’s mane, and the broader adaptogen/nootropic category — interesting research in some areas, but the evidence isn’t at the level I require for daily supplementation. I’m watching it, not yet taking it.
Collagen — the marketing is ahead of the science.
How I Verify This Is Working
None of this makes sense without testing. I get blood work done a couple of times a year that includes vitamin D, zinc, copper, ferritin, and a standard metabolic panel. This tells me whether what I’m taking is landing where I want it to, and whether anything needs adjusting.
If you want a comprehensive guide to which blood tests to ask for and what optimal ranges actually look like, I wrote a separate piece on that: The Longevity Blood Panel: What to Test and Why. And if you’re in Spain and need help navigating CatSalut, Sanitas, and private labs, there’s a practical guide for that too: A Practical Guide to Blood Testing in Spain.
Supplementing without testing is making decisions blindly. Start with a baseline. Then decide what you’re actually deficient in. Then supplement accordingly.
That’s the approach — evidence-based, tested, minimal. Five things on the list, all of them earning their place. Nothing more.
This article reflects my personal supplement choices and the reasoning behind them. It’s not medical advice. Talk to your doctor before starting any supplementation, particularly regarding dosing and interactions with medications.
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